Tape feed mechanisms



Oct. 16, 1962 G. PEREZ TAPE FEED MECHANISMS Original Filed Aug. 50, 1957CLUTCH MAGNET CURRENT Z R m op Q T O R m ms o E K T NL M M L W G g B I aF 0 6 3 fl/v I N w 5 D T A 9 a R T 0 4 \I m M S R o 1 R D F w W o w m SE S E 5 E U E T F L R m w m E E D R M R c T. E 3 U 0 M f C 9 H U 0 0 m A2 M T D E E F E P m United States Patent. Ofiice 3,058,362 TAPE FEEDMECHANISMS Guillermo Prez, Bristol, Conn., assignor to Royal McBeegorporation, Port Chester, N .Y., a corporation of New ork Originalapplication Aug. 30, 1957, Ser. No. 631,354, now Patent No. 2,997,231,dated Aug. 22, 1961. Divided and this application June 7, 1961, Ser. No.115,369 3 (Ilairns. (Cl. 74-142) This application is a division ofapplication Serial No. 681,354 filed August 30, 1957 and now Patent No.2,997,231.

This invention relates to tape feed mechanism, and more particularly itrelates to a tape feed mechanism having electromagnet means operative inconjunction with a drive member to couple tape indexing means to saiddrive member.

Heretofore electromagnetically operated tape feed mechanisms haveemployed electromagnets adapted when energized to mechanically drivepawl means into a ratchet wheel to effect an incremental movement of adrum to which the ratchet wheel is secured whereby a tape driven by thedrum is incrementally fed relative to a punching or reading station. Theemployment of electromagnets to perform such a power function requiresthat they be of considerable size and power whereby force suflicient toovercome the inertia of and to move the masses of the elements involvedcan be generated. Also the speed of operation in systems so constitutedis limited by the pull-in time of the electromagnet.

This invention embodies a novel construction of tape feed mechanismwhich permits an electromagnet of minimum size and power to be utilizedthereby to realize a very rapid and efiicient electromechanical couplingof a drive source with a tape indexing mechanism. Efficient use ofelectrical power is realized by utilizing the power of a cyclic drivesource to close and open the air gap between the electromagnet armatureand pole piece. In accordance with the invention the cyclic drive sourceis coupled to the electromagnet armature by a link connected between thearmature and a pawl rotatably mounted on but normally biased againstrotation rela tive to the drive source. The construction of the cyclicdrive source and associated elements is such that when the drive sourceis at one limit of its cycle, at which time the armature is adjacent itspole piece, and the electromagnet is energized, the armature isrestrained causing the pawl on the cyclic drive source to rotate andcouple the drive source to a ratchet as the drive source moves towardthe other limit of its cycle.

An object of the invention therefore is in the provision of a rapid andeflicient tape feed mechanism.

Another object of the invention is to provide a tape feed mechanismwherein only the holding power of an electromagnet is utilized to couplea drive source to a tape indexing mechanism.

A still further object of the invention i in the provision of a highspeed tape feed mechanism employing a pawl and ratchet constructionwherein the pawl couples a cyclic drive to the ratchet and incombination with the drive moves the ratchet through an increment.

Another object of the invention is in the provision of a pawl andratchet mechanism wherein the pawl is coupled to the ratchet mechanismby the action of a cyclic power source in conjunction with the holdingpower of an electromagnet.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings in which like reference nu-31358362 Patented Oct. 16, 1962 merals designate like parts throughoutthe figures thereof and wherein:

FIGURE 1 is a side view of a tape feed mechanism in accordance with theinvention showing the position of the elements when the cyclic drivesource is at one limit of its motion;

FIGURE 2 is a side view similar to FIGURE 1 showing the position of theelements when the cyclic drive source is at the other limit of itsmotion;

FIGURE 3 is a diagrammatic perspective view of the drive means; and

FIGURE 4 is a timing diagram explanatory of the operation of the tapefeed mechanism.

Referring now to the drawings wherein an exemplary embodiment isillustrated there is shown in FIGURES 1 and 2 a tape feed mechanismgenerally designated by reference numeral 10 operable under control of atape feed drive arm 11 and a tape feed electromagnet 12. As seen inFIGURE 3 the tape feed drive arm has a circular cutout 13 in its lowerend adapted to receive a circular cam 14 to which is eccentricallysecured a shaft 15. As the shaft 15 rotates through a 360 cycle the tapefeed drive arm 11 is driven through an up and down motion as illustratedby curve 16 in FIGURE 4. The electromagnet 12 is provided with anarmature 17 having one end pivotally mounted on the electromagnet frameas at 19 whereby the armature is movable toward and away from the polepiece 18 of the electromagnet. The tape feed mechanism comprises anactuator 20 rotatably mounted on the shaft 21 of a tape feed roll 22which has a ratchet wheel 23 concentrically secured thereto. A pawl 24is rotatably mounted intermediate its tail end 25 and its ratchetengaging end 26 to the actuator as at 29. The pawl is also articulatelycoupled to the free end of armature 17 by a link 27. A pawl biasingspring 28 is connected between a stud 30 on the tail end of the pawl anda cooperating stud 31 on the actuator whereby stud 3t abuts edge 32 ofthe actuator under the action of spring 28 and pawl 24 is properlypositioned relative to the ratchet wheel and biased against rotationrelative to the actuator. The pawl is also provided with a projection 33on its lower edge which is adapted to cooperate with a fixed stop bar 34suitably secured to a frame member (not shown). The actuator 20 isprovided with a stud 35 whereby it is rotatably connected to the tapefeed drive arm 11 which as heretofore stated is adapted to be driventhrough an up and down motion by the cam 14 and shaft 15. As shown inFIGURE 1 the normal position of the elements is such that the armatureis in zero air gap position.

Referring to FIGURE 3 the shaft 15 which powers drive arm 11 is adaptedto be coupled to a continuously rotating drive shaft 36 by a wrap springclutch which, as is well known to the art, comprises a helical couplingspring 3 7 wrapped concentrically about the drive 36 and driven shaft15. The ends of the spring 37 respectively are attached to a clutchcontrol disk 38 rotatably mounted on shaft 36 and a clutch control disk41 rotatably mounted on shaft 15. The normal diametral dimension of thespring is such that shafts 36 and 15 will be coupled thereby, withrotation of the shaft 36 serving to tighten the grip of the spring. Thespring is normally disengaged by relatively rotatively displacing thecontrol disks 38 and 41 in a direction which will expand the spring. Thespring is held in disengaged condition by a fixed and a rotatablymounted interponent 42 and 43 respectively which cooperate with steps 44on the periphcry of the disks 38 and 41 whereby relative rotation of thedisks under the action of the radially expanded spring is prevented.Interponent 43 comprises the armature of a clutch electromagnet, theenergization of which pulls interponent 43 out of engagement with itsassociated step on disk 41 whereupon the spring wraps and couples theshafts 36 and 15. As is understood in the art upon deenergization of theclutch electromagnet during a cycle interponent 43 will re-engage thestep on control disk 41 after the shaft 15 completes a 360 revolutionthereby to cause the spring to unwrap.

'The operation of the tape feed mechanism will now be explained,reference being directed to FIGURES 1, 2 and 4; FIGURE 4 showing thetimes of energization and de-energization of the clutch and feedelectromagnets related to angular degrees of rotation of shaft 15 andthe tape feed drive arm motion over one cycle resulting from rotation ofshaft 15.

Energization of the tape feed and clutch electromagnets may be effectedin response to signals periodically or aperiodically generated uponoperation of a business machine. It is to be here noted that wheresignals are p riodically generated at a constant rate the necessity forintermittently coupling shaft 15 to a continuously driven shaft 36 maybe dispensed with and shaft 15 itself may be continuously driven; thetape feed signals being delivered to the electromagnet 12 in synchronismwith the motion of the now continuously rotating shaft 15.

As is apparent from FIGURE 4 the energization of the clutchelectromagnet at time t results in a current (curve 49) therethroughwhich is sufficiently built up to pull its armature i.e. interponent 43from engagement with the clutch control disk 41 at time t, therebypermitting the spring to wrap and couple shafts 36 and 15 whereby acycle of the latter is started at time t After a cycle has started theclutch electromagnet may be deenergized whereby the drive and drivenshafts 36 and 15 respectively will be uncoupled at the end of a 360cycle. Since the tape feed electromagnet 12 is already energized at timet as illustrated by current curve 51, upon upward movement of the tapefeed drive arm 11 and rotation of the actuator 20 counterclockwise, thepawl, rotatably mounted on the actuator 20 and linked to the armature 17is restrained by the energized electromagnet, and rotates relative tothe actuator 20 under the action of the drive arm 11. When the drive arm11 reaches a position corresponding to 90 rotation of shaft 15 the pawlwill have rotated into engagement with the ratchet 23. Continuedrotation of shaft 15 to 180 moves the drive arm 11 further in the updirection as shown by curve 16 thereby continuing the counterclockwiserotation of the actuator, causing the pawl 24 to lock with and rotatethe ratchet 23 one tooth. As is apparent, after the pawl locks with theratchet, and while the pawl is rotating the ratchet, no further relativemovement of the pawl and actuator can occur thereby permitting, duringthe 90-180 feed interval, the forcible withdrawal of the armature 17away from the pole piece 18, until the electromagnet 12 is de-energized;the latter occurring when the drive arm reaches a position correspondingto 156 as shown by curve 51. After 180 rotation of shaft 15 the actuator20 begins a clockwise r tation due to the downward motion of arm 11.During the to 360 interval the pawl 24 is therefore disengaged from theratchet and returned to normal. As is apparent from FIGURE 2 which showsthe 180 position of shaft 15 overtravel of the ratchet 23 due to itsinertia is prevented by stop bar 34 which, when engaged by the pawlprojection 33, acts to increase the pressure of the pawl tooth 26 on theratchet 23.

It should be understood that the foregoing disclosure relates to only apreferred embodiment of the invention and that it is intended to coverall changes and modifications of the example of the invention hereinchosen for the purposes of the disclosure which do not constitutedepartures from the spirit and scope of the invention.

The invention claimed is:

l. Ratchet indexing mechanism comprising drive means, means oscillatingsaid drive means between predetermined limits of motion, a pawlrotatably mounted on said drive means, means normally biasing said pawlagainst rotation relative to said drive means, control means operativeat one limit of motion of said drive means to effect the rotation ofsaid pawl relative to said drive means as said drive means oscillatestoward its other limit of motion, and ratchet means engageable with anddriven by said rotated pawl.

2. A tape feed mechanism comprising a feed roll, a ratchetconcentrically mounted for movement with said roll, cyclically operablemeans rotatably mounted on the shaft of said feed roll, a pawl rotatablymounted on said cyclically operable means, means normally biasing saidpawl against rotation relative to said cyclically operable means, anelectromagnet and associated armature, link means for coupling said pawland armature, and means for driving said cyclically operable meansbetween predetermined limits, said electromagnet being adapted to beenergized at the beginning of a cycle of said cyclically operable meanswhereby as a cycle progresses said pawl is restrained by said armatureand caused to rotate relative to said cyclically operable means intodriving engagement with said ratchet.

3. A tape feed mechanism comprising a feed roll, a ratchetconcentrically mounted for movement with said feed roll, cyclicallyoperable means rotatably mounted on the shaft of said feed roll, a pawlrotatably mounted on said cyclically operable means, means normallybiasing said pawl against rotation relative to said cyclically operablemeans, control means operative at one limit of motion of said cyclicallyoperable means to effect rotation of said pawl relative to saidcyclically operable means as said cyclically operable means moves towardits other limit of motion, ratchet means engageable with and driven bysaid rotated pawl, and means operative in association with said pawl forpreventing inertial overtravel of said ratchet and feed roll.

No references cited.

